Bulk to interphase transition in polyamide 6 compounds with high filler content

The influence of aluminum borate whiskers upon the morphology of polyamide 6 was studied by wide-angle X-ray scattering and by differential scanning calorimetry. The whiskers did not promote the formation of either the hexagonal γ or the monoclinic β crystalline phase. A new experimental procedure has been devised for the production of very thin polymer layers on the whiskers. In the procedure, styrene co-acrylonitrile polymer is used as a processing aid and is later extracted. The procedure allows for the generation of polyamide layers less than 30 nm thick. Crystallinity in these thin layers was suppressed. An expression has been developed to characterize the crystallinity gradient in the interphase of the whisker surface. The equation shows that the initial 1.4 nm of polymer is fully amorphous and produces excellent evaluations of the crystallinity gradient to layer thicknesses of 70 nm.